Radio link monitoring in multiple transmitter receiver point scenario

Abstract

The present disclosure relates to techniques that enable an efficient Radio Link Monitoring (RLM) for a User Equipment (UE) in a multi Transmitter Receiver Point (mTRP) scenario. For this purpose, a serving cell of a serving Distributed Unit (DU) of a disaggregated network node and at least one non-serving (or stand-by) cell of a non-serving DU of the disaggregated network node are configured fora UE. Then, the UE is informed of beams used for the serving and non-serving cells. The UE performs the RLM over the serving cell by using the beams of the serving cell. Whenever there is an Radio Link (RL) quality degradation (which may potentially lead to an RL Failure (RLF)) detected in the serving cell, the UE may initiate switching of the RLM from the serving cell to one of the non-serving cells by transmitting a corresponding request to the serving DU.

1 - 21 . (canceled) 
     
     
         22 . A User Equipment (UE) in a wireless communication network, comprising:
 at least one processor; and   at least one memory including a computer program code;   wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the UE to:
 receive, from a Centralized Unit (CU) of a network node, configuration information indicative of: (i) at least one beam corresponding to a serving cell of a serving Distributed Unit (DU) of the network node, (ii) at least one beam corresponding to at least one non-serving cell of a non-serving DU of the network node; 
 perform Radio Link Monitoring (RLM) over the serving cell by using the at least one beam of the serving cell; 
 during the RLM, detect that there is a Radio Link (RL) quality degradation occurred in the serving cell; 
 transmit, to the serving DU, a request for switching the RLM from the serving cell to one of the at least one non-serving cell, the request comprising a signal measurement and an RLM report relating to the RL quality degradation; 
 receive, from the serving DU, a response indicative of a target cell among the at least one non-serving cell; and 
 switch the RLM from the serving cell to the target cell. 
   
     
     
         23 . The UE of  claim 22 , wherein the configuration information is further indicative of an RLM switching timer, and wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the UE to:
 trigger the RLM switching timer upon detecting the RL quality degradation in the serving cell; and   transmit the request to the serving DU after the RLM switching timer expires.   
     
     
         24 . The UE of  claim 23 , wherein the RLM switching timer is less than a T310 timer. 
     
     
         25 . The UE of  claim 22 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the UE to transmit the request by using at least one of Medium Access Control (MAC) Control Element (CE) and a Channel State Information (CSI) report. 
     
     
         26 . The UE of  claim 22 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the UE to transmit the request by using a Layer 1 (L1) or Layer 2 (L2)-based mechanism. 
     
     
         27 . The UE of  claim 22 , wherein the signal measurement comprises at least one of a Reference Signals Received Power (RSRP) and a Reference Signal Received Quality (RSRQ). 
     
     
         28 . A Centralized Unit (CU) of a network node disaggregated in a wireless communication network into a serving Distributed Unit (DU), a non-serving DU and the CU, wherein the CU comprises:
 at least one processor; and   at least one memory including a computer program code;   wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the CU to:
 generate configuration information indicative of: (i) at least one beam corresponding to a serving cell of the serving DU of the network node, (ii) at least one beam corresponding to at least one non-serving cell of the non-serving DU of the network node; 
 transmit the configuration information to a User Equipment (UE); 
 generate a criterion for the serving DU to select a target cell among the at least one non-serving cell, the criterion being used if the serving DU receives a request for switching Radio Link Monitoring (RLM) from the serving cell to one of the at least one non-serving cell from the UE; and 
 transmit the criterion to the serving DU. 
   
     
     
         29 . The CU of  claim 28 , wherein the configuration information is further indicative of an RLM switching timer to be used by the UE when a Radio Link (RL) quality degradation occurs in the serving cell of the serving DU. 
     
     
         30 . The CU of  claim 29 , wherein the RLM switching timer is less than a T310 timer. 
     
     
         31 . The CU of  claim 28 , wherein the criterion is defined as follows: an RL quality indicator for the target cell is above a threshold. 
     
     
         32 . A method for operating a User Equipment (UE) in a wireless communication network, comprising:
 receiving, from a Centralized Unit (CU) of a network node, configuration information indicative of: (i) at least one beam corresponding to a serving cell of a serving Distributed Unit (DU) of the network node, (ii) at least one beam corresponding to at least one non-serving cell of a non-serving DU of the network node;   performing Radio Link Monitoring (RLM) over the serving cell by using the at least one beam of the serving cell;   during the RLM, detecting that there is a Radio Link (RL) quality degradation occurred in the serving cell;   transmitting, to the serving DU, a request for switching the RLM from the serving cell to one of the at least one non-serving cell, the request comprising a signal measurement and an RLM report relating to the RL quality degradation;   receiving, from the serving DU, a response indicative of a target cell among the at least one non-serving cell; and   switching the RLM from the serving cell to the target cell.   
     
     
         33 . A method for operating a Centralized Unit (CU) of a network node disaggregated in a wireless communication network into a serving Distributed Unit (DU), a non-serving DU and the CU, wherein the method comprises:
 generating configuration information indicative of: (i) at least one beam corresponding to a serving cell of the serving DU of the network node, (ii) at least one beam corresponding to at least one non-serving cell of the non-serving DU of the network node;   transmitting the configuration information to a User Equipment (UE);   generating a criterion for the serving DU to select a target cell among the at least one non-serving cell, the criterion being used if the serving DU receives a request for switching Radio Link Monitoring (RLM) from the serving cell to one of the at least one non-serving cell from the UE; and   transmitting the criterion to the serving DU.   
     
     
         34 . A computer program product comprising a computer-readable storage medium, wherein the computer-readable storage medium stores a computer code which, when executed by at least one processor, causes the at least one processor to perform the method according to  claim 32 . 
     
     
         35 . A computer program product comprising a computer-readable storage medium, wherein the computer-readable storage medium stores a computer code which, when executed by at least one processor, causes the at least one processor to perform the method according to  claim 33 .